package api

import (
	"fmt"
)

type PullRequestsPayload struct {
	ViewerCreated   []PullRequest
	ReviewRequested []PullRequest
	CurrentPR       *PullRequest
}

type PullRequest struct {
	Number      int
	Title       string
	State       string
	URL         string
	HeadRefName string

	HeadRepositoryOwner struct {
		Login string
	}
	HeadRepository struct {
		Name             string
		DefaultBranchRef struct {
			Name string
		}
	}
	IsCrossRepository   bool
	MaintainerCanModify bool

	ReviewDecision string

	Commits struct {
		Nodes []struct {
			Commit struct {
				StatusCheckRollup struct {
					Contexts struct {
						Nodes []struct {
							State      string
							Conclusion string
						}
					}
				}
			}
		}
	}
}

func (pr PullRequest) HeadLabel() string {
	if pr.IsCrossRepository {
		return fmt.Sprintf("%s:%s", pr.HeadRepositoryOwner.Login, pr.HeadRefName)
	}
	return pr.HeadRefName
}

type PullRequestReviewStatus struct {
	ChangesRequested bool
	Approved         bool
	ReviewRequired   bool
}

func (pr *PullRequest) ReviewStatus() PullRequestReviewStatus {
	status := PullRequestReviewStatus{}
	switch pr.ReviewDecision {
	case "CHANGES_REQUESTED":
		status.ChangesRequested = true
	case "APPROVED":
		status.Approved = true
	case "REVIEW_REQUIRED":
		status.ReviewRequired = true
	}
	return status
}

type PullRequestChecksStatus struct {
	Pending int
	Failing int
	Passing int
	Total   int
}

func (pr *PullRequest) ChecksStatus() (summary PullRequestChecksStatus) {
	if len(pr.Commits.Nodes) == 0 {
		return
	}
	commit := pr.Commits.Nodes[0].Commit
	for _, c := range commit.StatusCheckRollup.Contexts.Nodes {
		state := c.State
		if state == "" {
			state = c.Conclusion
		}
		switch state {
		case "SUCCESS", "NEUTRAL", "SKIPPED":
			summary.Passing++
		case "ERROR", "FAILURE", "CANCELLED", "TIMED_OUT", "ACTION_REQUIRED":
			summary.Failing++
		case "EXPECTED", "QUEUED", "PENDING", "IN_PROGRESS":
			summary.Pending++
		default:
			panic(fmt.Errorf("unsupported status: %q", state))
		}
		summary.Total++
	}
	return
}

type Repo interface {
	RepoName() string
	RepoOwner() string
}

func PullRequests(client *Client, ghRepo Repo, currentBranch, currentUsername string) (*PullRequestsPayload, error) {
	type edges struct {
		Edges []struct {
			Node PullRequest
		}
		PageInfo struct {
			HasNextPage bool
			EndCursor   string
		}
	}

	type response struct {
		Repository struct {
			PullRequests edges
		}
		ViewerCreated   edges
		ReviewRequested edges
	}

	query := `
	fragment pr on PullRequest {
		number
		title
		url
		headRefName
		headRefName
		headRepositoryOwner {
			login
		}
		isCrossRepository
		commits(last: 1) {
			nodes {
				commit {
					statusCheckRollup {
						contexts(last: 100) {
							nodes {
								...on StatusContext {
									state
								}
								...on CheckRun {
									conclusion
								}
							}
						}
					}
				}
			}
		}
	}
	fragment prWithReviews on PullRequest {
		...pr
		reviewDecision
	}
    query($owner: String!, $repo: String!, $headRefName: String!, $viewerQuery: String!, $reviewerQuery: String!, $per_page: Int = 10) {
      repository(owner: $owner, name: $repo) {
        pullRequests(headRefName: $headRefName, states: OPEN, first: 1) {
          edges {
            node {
              ...prWithReviews
            }
          }
        }
      }
      viewerCreated: search(query: $viewerQuery, type: ISSUE, first: $per_page) {
        edges {
          node {
            ...prWithReviews
          }
        }
        pageInfo {
          hasNextPage
        }
      }
      reviewRequested: search(query: $reviewerQuery, type: ISSUE, first: $per_page) {
        edges {
          node {
            ...pr
          }
        }
        pageInfo {
          hasNextPage
        }
      }
    }
  `

	owner := ghRepo.RepoOwner()
	repo := ghRepo.RepoName()

	viewerQuery := fmt.Sprintf("repo:%s/%s state:open is:pr author:%s", owner, repo, currentUsername)
	reviewerQuery := fmt.Sprintf("repo:%s/%s state:open review-requested:%s", owner, repo, currentUsername)

	variables := map[string]interface{}{
		"viewerQuery":   viewerQuery,
		"reviewerQuery": reviewerQuery,
		"owner":         owner,
		"repo":          repo,
		"headRefName":   currentBranch,
	}

	var resp response
	err := client.GraphQL(query, variables, &resp)
	if err != nil {
		return nil, err
	}

	var viewerCreated []PullRequest
	for _, edge := range resp.ViewerCreated.Edges {
		viewerCreated = append(viewerCreated, edge.Node)
	}

	var reviewRequested []PullRequest
	for _, edge := range resp.ReviewRequested.Edges {
		reviewRequested = append(reviewRequested, edge.Node)
	}

	var currentPR *PullRequest
	for _, edge := range resp.Repository.PullRequests.Edges {
		currentPR = &edge.Node
	}

	payload := PullRequestsPayload{
		viewerCreated,
		reviewRequested,
		currentPR,
	}

	return &payload, nil
}

func PullRequestByNumber(client *Client, ghRepo Repo, number int) (*PullRequest, error) {
	type response struct {
		Repository struct {
			PullRequest PullRequest
		}
	}

	query := `
	query($owner: String!, $repo: String!, $pr_number: Int!) {
		repository(owner: $owner, name: $repo) {
			pullRequest(number: $pr_number) {
				headRefName
				headRepositoryOwner {
					login
				}
				headRepository {
					name
					defaultBranchRef {
						name
					}
				}
				isCrossRepository
				maintainerCanModify
			}
		}
	}`

	variables := map[string]interface{}{
		"owner":     ghRepo.RepoOwner(),
		"repo":      ghRepo.RepoName(),
		"pr_number": number,
	}

	var resp response
	err := client.GraphQL(query, variables, &resp)
	if err != nil {
		return nil, err
	}

	return &resp.Repository.PullRequest, nil
}

func PullRequestsForBranch(client *Client, ghRepo Repo, branch string) ([]PullRequest, error) {
	type response struct {
		Repository struct {
			PullRequests struct {
				Edges []struct {
					Node PullRequest
				}
			}
		}
	}

	query := `
    query($owner: String!, $repo: String!, $headRefName: String!) {
      repository(owner: $owner, name: $repo) {
        pullRequests(headRefName: $headRefName, states: OPEN, first: 1) {
          edges {
            node {
				number
				title
				url
            }
          }
        }
      }
    }`

	variables := map[string]interface{}{
		"owner":       ghRepo.RepoOwner(),
		"repo":        ghRepo.RepoName(),
		"headRefName": branch,
	}

	var resp response
	err := client.GraphQL(query, variables, &resp)
	if err != nil {
		return nil, err
	}

	prs := []PullRequest{}
	for _, edge := range resp.Repository.PullRequests.Edges {
		prs = append(prs, edge.Node)
	}

	return prs, nil
}

func CreatePullRequest(client *Client, ghRepo Repo, params map[string]interface{}) (*PullRequest, error) {
	repoID, err := GitHubRepoId(client, ghRepo)
	if err != nil {
		return nil, err
	}

	query := `
		mutation CreatePullRequest($input: CreatePullRequestInput!) {
			createPullRequest(input: $input) {
				pullRequest {
					url
				}
			}
	}`

	inputParams := map[string]interface{}{
		"repositoryId": repoID,
	}
	for key, val := range params {
		inputParams[key] = val
	}
	variables := map[string]interface{}{
		"input": inputParams,
	}

	result := struct {
		CreatePullRequest struct {
			PullRequest PullRequest
		}
	}{}

	err = client.GraphQL(query, variables, &result)
	if err != nil {
		return nil, err
	}

	return &result.CreatePullRequest.PullRequest, nil
}

func PullRequestList(client *Client, vars map[string]interface{}, limit int) ([]PullRequest, error) {
	type response struct {
		Repository struct {
			PullRequests struct {
				Edges []struct {
					Node PullRequest
				}
				PageInfo struct {
					HasNextPage bool
					EndCursor   string
				}
			}
		}
	}

	query := `
    query(
		$owner: String!,
		$repo: String!,
		$limit: Int!,
		$endCursor: String,
		$baseBranch: String,
		$labels: [String!],
		$state: [PullRequestState!] = OPEN
	) {
      repository(owner: $owner, name: $repo) {
        pullRequests(
			states: $state,
			baseRefName: $baseBranch,
			labels: $labels,
			first: $limit,
			after: $endCursor,
			orderBy: {field: CREATED_AT, direction: DESC}
		) {
          edges {
            node {
				number
				title
				state
				url
				headRefName
				headRepositoryOwner {
					login
				}
				isCrossRepository
            }
		  }
		  pageInfo {
			  hasNextPage
			  endCursor
		  }
        }
      }
    }`

	prs := []PullRequest{}
	pageLimit := min(limit, 100)
	variables := map[string]interface{}{}
	for name, val := range vars {
		variables[name] = val
	}

	for {
		variables["limit"] = pageLimit
		var data response
		err := client.GraphQL(query, variables, &data)
		if err != nil {
			return nil, err
		}
		prData := data.Repository.PullRequests

		for _, edge := range prData.Edges {
			prs = append(prs, edge.Node)
			if len(prs) == limit {
				goto done
			}
		}

		if prData.PageInfo.HasNextPage {
			variables["endCursor"] = prData.PageInfo.EndCursor
			pageLimit = min(pageLimit, limit-len(prs))
			continue
		}
	done:
		break
	}

	return prs, nil
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}